How to use spray foam insulation to make your home more energy efficient
It is often easy to dismiss the slightest hint of a draft from a light switch or outlet box. Or, the small amount of air movement from an entrance door. Maybe some windows are a little drafty. Individually they don’t appear to be a major concern. But, in reality, most homes in the United States have enough of these little drafts that when accumulated is the same as having a window wide open all day, every day.
Just imagine the cost to heat a Minnesota home in January when a window is open the entire time. Or the cost to cool a Florida home in July with a window left open. This is why it is so important to properly seal a thermal envelope in new and existing homes.
Utility bills are significantly reduced with a sealed thermal envelope. Other added benefits include better humidity control and reduced noise from the outside. A sealed home will have less pollen, dust and insects (or pests) entering. And for the colder climate homes, proper insulation lowers the chance for ice dams on the roof and eves.
Spray foam insulation accomplishes two critical requirements for a properly sealed thermal envelope: it insulates very well and seals the small openings that other insulations cannot do in one step. It also does not settle over time. Fiberglass insulation is often installed inadequately, requiring more steps to achieve the performance of spray foam insulation.
Spray polyurethane foam insulation products are effective at both sealing and insulating. They are sprayed into the wall cavity as a liquid that expands multiple times its original size in seconds. As it expands, it conforms and fills cavities and voids to create a sealed thermal envelope. Spray foam insulation creates a highly effective seal against air infiltration, the number one source of energy loss in a structure. This insulation adheres to any clean, dry surface and will not sag or settle.
As an inert, thermoset plastic, spray foam products maintain their properties throughout the life of the building. Closed cell insulations been proven to add structural integrity throughout the wall system. Tests by the National Association of Home Builders Research Center in 1992, 1996 and 2005 show spray-applied foam between wood and steel stud wall panels increase rack and sheer strength two to three times compared to traditional stick-built components with fiberglass insulation when sprayed on to gypsum wall board and vinyl siding, and increased racking strength when sprayed on to oriented OSB.
Moisture tends to accumulate in wall cavities with fiberglass insulation when warm, moist air is exchanged with cold, dry air. Such moisture can condense within the walls, creating mildew, rot and mold. Properly applied spray foam insulation provides such a tight air seal that moisture condensation in walls is greatly minimized. Most if not all spray foam insulations are inert substances and do not support mold. In addition, they provide no food value for rodents and insects.
Spray foam can reduce monthly heating and cooling bills by up to 50 percent when used with other efficient construction components, compared with traditionally insulated and constructed structures. Additional savings can sometimes be realized by reducing the required size of the HVAC unit due to the spray foam’s efficiency. Other building materials may be reduced or eliminated such as soffit vents, ridge vents, attic ventilation fans, radiant barriers or vapor retarders when foam is used. This sealed envelope gives the HVAC system and your ventilation system full control over the amount and filtration of fresh air coming into the structure; helping to maintain good indoor air quality by blocking and then filtering harmful outside irritants such as mold, pollen or other allergens.
Most spray foam insulation products are Class I fire rated. They will char if exposed to a flame but will not sustain a flame. Flame retardants are added to the product to help ensure that they meet or exceed the applicable building code requirements for this type of product.
Installation of closed cell insulation
Application of these spray foam insulations takes place after the electrical, plumbing and mechanical systems are installed, but before sheetrock is started. Polyurethane foam is compatible with electrical wiring plastic. A certified electrical contractor can pull wire through spray foam insulation if wiring is installed after spray foam is applied to an existing home. For wires that may be moved frequently, such as home theater wiring, ENT conduit should be place in the wall before the insulation is installed.
Spray foam insulation should be installed by a contractor trained by the manufacturer to follow all application and safety instructions. Work with your local approved contractor to determine which product works best for your specific application and climate.
Read more about insulation.